Preheat oven to 350 degrees. In a medium bowl, whisk together ground flax and yogurt and set aside for 10 to 15 minutes to thicken.
Place 3/4 cup of the oats into a spice grinder or food processor and grind until you get coarse flour. Place in a medium mixing bowl and add remaining ¾ cup oats, teff flour, almond flour, baking powder, baking soda, cinnamon, and salt. Stir to combine and set aside.
Add sweet potato puree, olive oil, maple syrup, vanilla, vinegar. Whisk to combine and pour into dry mixture, stir until just combined.
Grease 12 cup muffin tin with olive oil, and spoon batter into muffins. I usually get 8 full size muffins when I fill them to the top. Bake for 28-30 minutes, until a toothpick comes outs clean.
Let cool in pan for 10 minutes, and use a knife to remove them by circling around the inside edges.
When muffins are fully cool, whisk icing ingredients together and lightly frost. The mixture might seem thick, but it changes from thick to runny quickly according to how much milk you add. Adjust as needed.